Block scoped declarations (let, const, function,class) not yet supported outside strict mode

[bralat]

Bug Report

I have read:

• Usage information
• Help information

I am using the latest version of the library.
v 0.26.0

Expected Behavior

I was trying to run the bot after writing some lines of code. I expected that after runningnode index.js,
there will be no errors and when i send a request from telegram, get the desired result.

Actual Behavior

what happened instead was this error in the console

class TelegramBot extends EventEmitter {
^^^^^

SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:373:25)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Module.require (module.js:353:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (E:\Code\dobo\node_modules\node-telegram-bot-api\index.js:12:20)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)

So i run this instead node --use_strict index.js and got different set of errors

constructor(token, options = {}) {
                             ^

SyntaxError: Unexpected token =
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:373:25)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Module.require (module.js:353:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (E:\Code\dobo\node_modules\node-telegram-bot-api\index.js:12:20)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)

So after a while, I went through telegram.js and telegramPolling.js and changed the following function parameters

1. options = {} to options
2. forms = {} to forms
3. fileOpts = {} to fileOpts

and in some cases, initialized the variable to an empty object within the function. For example

startPolling(options) {
    options = {};
    if (this.hasOpenWebHook()) {
      return Promise.reject(new Error('Polling and WebHook are mutually exclusive'));
    }
    options.restart = typeof options.restart === 'undefined' ? true : options.restart;
    if (!this._polling) {
      this._polling = new TelegramBotPolling(this._request.bind(this), this.options.polling, this.processUpdate.bind(this));
    }
    return this._polling.start(options);
  }

It was after taking these steps that it finally worked

Steps to reproduce the Behavior

1. write an index.js file with following code

var token = '<insert token here>';

var Bot = require('node-telegram-bot-api'),
    bot = new Bot(token, { polling: true });

bot.onText(/^\/say_hello (.+)$/, function (msg, match) {
  var name = match[1];
  bot.sendMessage(msg.chat.id, 'Hello ' + name + '!').then(function () {
    // reply sent!
  });
});

2. run node index.js

Question

My project, as at now, only tests sending messages but I could test other features If given approval

[preco21]

What node version are you currently using?

[bralat]

@preco21 node version 4.4.3

[preco21]

@CrazyAbdul I guess some of features are not supported in node@4: https://kangax.github.io/compat-table/es6/#node4

Could you upgrade your node to version 6 or 7?

[yagop]

Would be better to target a 4.x Node.js version.
For some reason, Travis tests for version 4.x are passing.
What do you think @GochoMugo ?

[preco21]

node-telegram-bot-api/index.js

Lines 7 to 11 in 2a782fd

	if (majorVersion === '0') {
	const deprecate = require('depd')('node-telegram-bot-api');
	deprecate('Node.js v0.12 and below will no longer be supported in the future');
	module.exports = require('./lib/telegram');
	} else {

Seems fallbacks in index.js only works when if the node version is 0.x.

Still have no idea for about TravisCI..

[preco21]

Maybe this opts file is causing the problem? It is requiring babel-register internally, so I guess this is reason how it could worked even on node v4.

[GochoMugo]

@preco21 Thanks for looking into this issue. It seems Node v4 does not support the syntax fully.

We can have the fallback work also for Node v4.x. However, I was hoping to only deprecate Node v0.x! Do we deprecate v4.x too?

Also, we should check if it runs on v5.x, v6.x, v7.x!

[bralat]

@preco21 It seems the quickest solution for me is to upgrade node to version 6. I'll update this thread on how it turns within the next few hours.

[GochoMugo]

If you can use the latest version of Node, I would suggest you go with that. However, since we are promising our users that we support Node v4.x, we need to fix this.

[bralat]

@GochoMugo I could look into adding support for node v4 upwards

[GochoMugo]

@CrazyAbdul We could really do with some help! Thanks in advance!

[GochoMugo]

@CrazyAbdul But we should discuss how to achieve that, to avoid having you do so much work only to be discarded!

[preco21]

What about simply do:

const majorVersion = process.versions.node.split('.')[0];
if (majorVersion === '0') {
  const deprecate = require('depd')('node-telegram-bot-api');
  deprecate('Node.js v0.12 and below will no longer be supported in the future');

  module.exports = require('./lib/telegram');
} else if (majorVersion === '4') {
  module.exports = require('./lib/telegram');
} else {
  module.exports = require('./src/telegram');
}

or even:

const majorVersion = process.versions.node.split('.')[0];

if (majorVersion === '0') {
  const deprecate = require('depd')('node-telegram-bot-api');
  deprecate('Node.js v0.12 and below will no longer be supported in the future');
}

module.exports = require(majorVersion === '0' || majorVersion === '4' ? './lib/telegram' : './src/telegram');

Also, you may need to fix mocha config to correct TravisCI.

[bralat]

@GochoMugo you earlier mentioned something about a fallback. What versions of node are those fallbacks for and how were they implemented. I'd want to learn from what the team has done so far before coming with a plan